Control unit for vehicle brake system

ABSTRACT

A control unit having a circuit substrate mounted within a housing that is adapted to be mounted upon a hydraulic valve body with a coil spacer mounted upon said substrate. The coil spacer including at least one coil support ring having resilient member extending in a radial direction from the edge of the ring into the center of the ring. The control unit also including a solenoid coil and flux casing assembly mounted upon the coil spacer ring with the solenoid coil and flux casing assembly flexing the resilient member such that the resilient member urges flux casing away from the coil spacer.

BACKGROUND OF THE INVENTION

This invention relates in general to a solenoid coil assembly includedin a vehicle anti-lock brake system and more particularly to a solenoidcoil assembly that provides compensation for manufacturing tolerances.

An anti-lock brake system (ABS) is often included as standard equipmenton new vehicles. When actuated, the ABS is operative to control theoperation of some or all of the vehicle wheel brakes. A typical ABSincludes a plurality of normally open and normally closed solenoidvalves which are mounted within a control valve body and connected tothe vehicle hydraulic brake system. Usually, a separate hydraulicsource, such as a motor driven pump, is included in the ABS forreapplying hydraulic pressure to the controlled wheel brakes during anABS braking cycle. The pump is typically included within the controlvalve body while the pump motor is mounted upon the exterior of thecontrol valve body.

An ABS further includes an Electronic Control Unit (ECU) which has amicroprocessor. The control unit is electrically coupled to the pumpmotor, a plurality of solenoid coils associated with the solenoid valvesand wheel speed sensors for monitoring the speed and deceleration of thecontrolled wheels. The control unit is typically mounted upon thecontrol valve body to form a compact unit which is often referred to asan ABS electro-hydraulic control unit or Hydraulic Control Unit (HCU).

During vehicle operation, the microprocessor in the ABS ECU continuouslyreceives speed signals from the wheel speed sensors. The microprocessormonitors the wheel speed signals for a potential wheel lock-upcondition. When the vehicle brakes are applied and the microprocessorsenses an impending wheel lock-up condition, the microprocessor isoperative to actuate the pump motor and selectively operate the solenoidvalves in the control unit to cyclically relieve and reapply hydraulicpressure to the controlled wheel brakes. The hydraulic pressure appliedto the controlled wheel brakes is adjusted by the operation of thesolenoid valves to limit wheel slippage to a safe level while continuingto produce adequate brake torque to decelerate the vehicle as desired bythe driver.

As described above, an ABS typically includes a plurality of solenoidvalves for controlling the flow of hydraulic fluid to the vehicle wheelbrakes. Solenoid valves are electrically actuated by supplying anenergizing current to a solenoid coil assembly. A typical coil assemblyincludes a coil in the form of an insulated magnet wire wound on aninsulated bobbin. The bobbin supports a pair of terminal leads. The endsof the coil magnet wire are wound upon the terminal leads. The terminalleads are connected through an electronic switch to a voltage supply.When the electronic switch is in a conducting state, current passesthrough the magnet wire and produces a magnetic field.

Solenoid valves also include an axially shiftable armature that isdisposed within a valve sleeve. The solenoid coil assembly is carried bythe valve sleeve. The armature is biased by spring to maintain a valveball in a normally opened or closed position. The valve ball is adaptedto cooperate with a valve seat member, which is provided in a valvebody. The solenoid coil assemblies are typically enclosed within acup-shaped a flux return casing. An annular flux ring is often disposedwithin an open end of the flux casing. The annular flux ring completes amagnetic flux path that is adapted to pass through the armature and thevalve seat member.

To actuate the valve, electric current is supplied through the terminalleads to the solenoid coil. The current establishes a magnetic field inthe armature, which pulls the armature against the force of the springto open or close the valve ball. An interruption in the current causesthe magnetic field to collapse. This allows the spring to return thearmature to its normal position.

To insure proper operation of the valve, the armature and sleeve mustfit within a close tolerance of the bobbin. The bobbin must fit within aclose tolerance of the flux return casing. Moreover, the annular fluxring, the flux return casing, the armature, and the valve seat membermust make sufficient contact with one another to assure an optimal fluxpath.

A plurality of valves are usually mounted upon a hydraulic control unit.Each of the valves is controlled by a separate solenoid coil assembly.The coil assemblies are typically controlled by an electronic controlunit. The electronic control unit is often coupled to the coilassemblies via a lead frame or printed circuit board that supports aplurality of coil assemblies. The lead frame or printed circuit boardincludes a pair of holes for receiving the terminals of each of thesolenoid coil assemblies.

A problem exists with positioning the coil assemblies relative torespective valves due to manufacturing tolerances. For example, theterminals of a plurality of coil assemblies are connected to a leadframe or a multi-chip module. A plurality of valves are mounted upon bya hydraulic control unit. Each of the coil assemblies, though connectedto the lead frame or multi-chip module, must align with a correspondingvalve sleeve. This often requires that a certain amount of play orspacing exist between the coil assembly bobbins and the valve sleeves asa result of manufacturing tolerances. The play reduces the magneticfield established in the armature. In addition, an inability to controlthe position of the flux return casings relative to their respectivevalve seats may result in insufficient contact between the flux returncasings and the valve seats. This further reduces the magnetic fieldestablished in the armature.

A coil assembly is needed that fits snuggly about the valve cartridgearmature and that encounters minimal axial translation resulting frommanufacturing tolerances to maximize the magnetic flux through the valvearmature.

SUMMARY OF THE INVENTION

The present invention is directed toward a solenoid coil assembly thatprovides compensation for manufacturing tolerances.

The present invention contemplates a coil assembly that comprises a coilwound upon a bobbin. A pair of terminals is supported by the bobbin. Thecoil has a pair of lead wires, each of which is connected to one of theterminals. Each terminal is adapted to be coupled to an electroniccontrol unit. The coil is enclosed at least in part by a flux returncasing. At least one resilient member is arranged and configured to urgethe bobbin and the casing axially downward.

The present invention also contemplates an electronic control unit thatincludes a housing adapted to be mounted upon a hydraulic valve body. Acircuit substrate is mounted within the housing and a coil spacer ismounted upon the circuit substrate. The coil spacer includes at leastone coil support ring having a resilient member extending in a radialdirection from the edge of the ring into the center of the ring. Asolenoid coil and flux casing assembly is mounted upon the coil spacerring with the coil flexing the resilient member such that the resilientmember urges the flux casing away from the coil spacer and toward thehydraulic valve body. In the preferred embodiment, the coil spacer alsoincludes an electrical connector for at least one pressure sensor and anelectrical connector for a pump motor.

The present invention further contemplates a method for assembling anelectronic control unit that includes providing at least one solenoidcoil and mounting the solenoid coil upon a coil spacer. The coil spaceris mounted upon a circuit substrate to form an assembly and the assemblyis inserted into a housing. As a further step, the housing is mountedupon a hydraulic valve body to form a hydraulic control unit.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a self-locating coil assemblyaccording to the invention carried by a solenoid valve that is supportedby a valve body.

FIG. 2 is a perspective view of the coil assembly shown in FIG. 1.

FIG. 3 is a front elevational view of the coil assembly shown in FIGS. 1and 2.

FIG. 4 is a side elevational view of the coil assembly shown in FIGS.1-3.

FIG. 5 is a side elevational view of an alternative embodiment of thecoil assembly.

FIG. 6 is a side elevational view of yet another alternate embodiment ofthe coil assembly.

FIG. 7 is an exploded view of an Electronic Control Unit that includesan alternate embodiment of the invention.

FIG. 8 is a side view of a coil spacer that is shown in FIG. 7.

FIG. 9 is a bottom view of the coil spacer that is shown in FIG. 8.

FIG. 10 is a perspective view of the coil spacer shown in FIGS. 7 and 8as seen from below.

FIG. 11 is a enlarged partial view of the coil spacer shown in FIG. 10.

FIG. 12 is view of a printed circuit board that is shown in FIG. 7.

FIG. 13 is a perspective view of a housing that is shown in FIG. 7 asseen from below.

FIG. 14 is a sectional assembly view of the components shown in FIG. 7.

FIG. 15 is an enlarged perspective view of a portion of FIG. 15.

FIG. 16 is a fragmentary perspective view of a coil and flux ringassembly that is shown in 14.

FIG. 17 is a flow chart for a method of assembly for the ElectronicControl Unit shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown a sectional view of a solenoidvalve 10 mounted upon a valve body 12. The valve 10 includes an axiallyshiftable armature 14, which is biased in an upward direction by abiasing element, such as the spring 16 shown. The spring 16 maintains avalve ball 18 in a normally opened position. Alternatively, a biasingelement may be provided to maintain the valve ball 18 in a normallyopened position. The valve ball 18 is adapted to cooperate with a valveseat member 20, which is provided in the valve body 12. The armature 14is adapted to slide within a valve sleeve 22.

A coil assembly is carried by the valve sleeve 22. The coil assemblyincludes a solenoid coil 24. The coil 24 may be comprised of a coilwinding 30 formed from multiple turns of an insulated magnet wire havinga round cross-section, such as # 28½ magnet wire. The coil wire ispreferably a helical coil wound upon a bobbin 32. The bobbin 32 isformed of a non-conductive material. The bobbin 32 supports a pair ofterminal supports 34. Each of the supports 34 is adapted to support aterminal 36. A lead wire (not shown) of the coil winding 30 is woundaround a lower end of the terminals 36 and soldered thereto. Anyremaining portion of the lead wires may be tucked into a channel 40bounded between two vertically spaced flanges 42, 44 at the upper end ofthe bobbin 32. An upper end of each terminal 36 may be coupled to anelectrical control unit, such as by a lead frame or multi-chip module.

The lead frame or multi-chip module may support a plurality of coils forcontrolling a plurality of valves in a hydraulic control unit. The leadframe or multi-chip module would include a pair of holes for receivingeach pair of terminals. In a preferred embodiment of the invention, theterminals 36 are compliant to enable the coil assembly to be positionedrelative to a corresponding valve. The particular terminals 36illustrated include an intermediate portion 38 that is extendable,retractable, and laterally displaceable. This is accomplished byproviding segments of the intermediate portion 38 that bend and overlap.Although other configurations are conceivable, the segments bend andoverlap to form a substantially S-shaped configuration that isextendable, retractable, and laterally displaceable.

The coil 24 is enclosed at least in part by a metal flux return casing26. An annular flux ring 28 is disposed within an opening at the upperend of the bobbin 12. The flux ring 28 is adapted to engage the fluxreturn casing 26. The flux ring 28 and the flux return casing 26 may beof unitary construction. The flux return casing 26 and flux ring 28complete a magnetic flux path that passes through the armature 14 andthe valve seat member 20.

To actuate the valve 10, electric current is supplied through theterminals 36 to the coil 24. The current establishes a magnetic field inthe armature 14, which pulls the armature 14 in a downward direction,closing the valve ball 18. An interruption in the current causes themagnetic field to collapse. This allows the spring 16 to return thearmature 14 to its original position, thereby reopening the valve ball18. Other solenoid valves, such as normally closed solenoid valves, mayhave structures similar to the normally open valve 10 described above.

In accordance with a preferred embodiment of the present invention, thebobbin 32 is provided with a resilient member, such as a spring, thatminimizes axial translation of the bobbin 32. As illustrated in FIGS.2-4, a pair of springs 46 is supported by the upper end of the bobbin32. The springs 46 are supported in spaced relation to one another by anuppermost flange 42. Each spring 46 is in the form of an elongateresilient member extending in an upward direction from the uppermostflange 42. A lower end of each spring 46 is preferably molded to theupper flange 44. An intermediate portion 48 of each spring 46 isdisposed at an angle between 0 and 90 degrees relative to the uppermostflange 42. An upper end of each spring 46 may be bent to form asubstantially horizontally extending portion. The horizontally extendingportion defines a contact member 50 that is adapted to engage the leadframe or multi-chip module upon coupling the terminals 36 to the leadframe or multi-chip module. A curved region 52 of each spring 46provides a smooth transition between the intermediate portion 48 and thecontact member 50.

Upon compressing the springs 46, the lead frame or multi-chip module maysmoothly traverse the curved region 52. The compressed springs 46 urgethe bobbin 32 axially downward along the valve armature 14 and cause themetal flux return casing 26 to contact the valve seat member 20 tocomplete a magnetic flux return path that is adapted to pass through thearmature 14 and the valve seat member 20. The magnetic flux path must besufficient to pull the armature 14 against the force of the spring 46 toopen or close the valve ball 18.

An alternative embodiment of the invention is illustrated in FIG. 5.According to this embodiment, a single helical spring 54 is supported bythe upper end of a flux return casing 56. The spring 54 is adapted to becompressed between the casing 56 and the lead frame or multi-chipmodule. When compressed, the spring 54 urges the coil assembly axiallydownward. The casing 56 is urged into contact with the valve seat member58 and the flux ring 60 in the opening at the upper end of the bobbin62. Similar to the springs 46 of the foregoing embodiment, the spring 54of this embodiment functions to position or locate the coil assembly.

Yet another embodiment of the invention is illustrated in FIG. 6. Thisembodiment includes a metal helical spring 64. The spring 64 isdimensioned to receive the armature (not shown) and adapted to becompressed between the bobbin 66 and a metal plate 68. The plate 68 isadapted to engage a metal flux return casing 70. The flux return casing70, the spring 64, and the plate 68 complete a magnetic flux path thatpasses through the armature (not shown) and the valve seat member 72.The spring 64 according to this embodiment of the invention functions toposition the coil assembly and complete the magnetic flux path.

Another alternate embodiment of the invention is illustrated in FIG. 7where an exploded view of an Electronic Control Unit (ECU) 80 is shown.The ECU 80 includes a coil spacer 82 that is disposed between a PrintedCircuit Board (PCB) 84 and a plurality of solenoid coil assemblies 86.Each of the solenoid coil assemblies 86 includes a solenoid coil 88 thatis received within a corresponding cup-shaped flux casing 90. The PCB 84is mounted within a housing 92, as will be described below. A pluralityof threaded fasteners 94 removablely secure the assembled ECU 80 to ahydraulic valve body 95, as shown in FIG. 14, to form a hydrauliccontrol unit for a vehicle brake system. As described above, in thepreferred embodiment, the ECU 80 and associated hydraulic valve body 95are included in a vehicle anti-lock brake system. However, dependingupon the configuration of the ECU 80 and the associated hydraulic valvebody 95, the hydraulic control unit may also be used in a tractioncontrol system and/or a vehicle stability control system.

Details of the coil spacer 82 are shown in FIGS. 8 through 11. The coilspacer 82 includes a base 96 having a lattice-like structure. In thepreferred embodiment, the coil spacer base 96 is injection molded in onepiece from a plastic material. The base 96 includes a plurality ofcircular coil support rings 98 connected by webs 100 that extend in aradial direction from the rings 98. A motor electrical connector base102 is disposed between two of the coil support rings 98. A pair ofpressure sensor electrical connector bases 104 are also connected bywebs 100 to coil support rings 98.

The motor electrical connector base 102 carries a pair of spadeconnectors 106 that provide electrical contact between a pump motorconnector (not shown) and associated traces deposited upon the PCB 84.As best seen in FIG. 8, the spade connectors 106 extend above the uppersurface of the connector base 102. As will be described below, the endsof the spade connectors 106 extend through corresponding aperturesformed through the PCB 84 and into electrical contact with traces uponthe PCB 84.

In the preferred embodiment, only one of the pressure sensor connectorbases 104 carries electrical connectors 108 since the unit is intendedfor use with a hydraulic valve body having a single pressure sensor.However, the base 96 is designed to support two pressure sensors bysimply adding a set of electrical connectors 108 to the second base 104.Alternately, the invention may be practiced with a base 96 that includesonly one pressure sensor connector base (not shown) or three or morepressure sensor connector bases (also not shown). Similar to the motorspade connectors 106, the electrical connectors 108 include a pluralityof pins 109 that extend above the connector base 104 and through the PCB84 to form an electrical connection with associated traces.

An enlarged perspective drawing one of the coil support rings 98 isshown in FIG. 11. The view of FIG. 11 is taken as looking upward towardthe lower surface of the base 96. An aperture 110 is formed through thecenter of the coil support ring 98. A finger 112 extends radially fromthe circumference of the aperture 110 into the center thereof. Asemicircular tab 114 is formed upon the end of the finger 112 andextends in a downward direction in FIG. 11. Upon assembly of the ECU 80onto the hydraulic valve body 95, the finger 112 is flexed in the upperdirection by an associated solenoid coil flux casing 90 (not shown). Theresiliency of the plastic forming the finger 112 causes the tab 114 toexert a downward force upon the flux casing 90, urging the casing 90into contact with an associated solenoid valve sleeve 202, asillustrated in FIG. 14. An inner raised portion 116 and an outer raisedportion 118 are formed upon the surface of the coil support ring 98 andextend along the connecting webs 100. The raised portions 116 and 118add rigidity to the coil spacer 82 while allowing removal of materialtherebetween to reduce weight.

A kidney-shaped opening 120 is formed through a portion of the coilsupport ring 98. As best seen in FIG. 11 a rectangular spacer 122extends in an upward direction from the center of the opening 120. Uponassembly of the ECU 80, the spacer contacts the lower surface of the PCB84 and cooperates therewith to vertically offset the base 96 from thePCB 84. A pair of crush ribs 124 extend into the opening 120 fromopposite ends thereof. The opening 120 receives a coil lead supporttower (not shown) formed upon a solenoid coil bobbin. The crush ribs 124cooperate with the coil lead support tower to retain the coil upon thecoil spacer 82 during assembly of the ECU 80. Similarly, a locator bore126 extends into a spacer post 128 that is formed upon the coil supportring 98 across the aperture 110 from the kidney-shaped opening 120. Thelocator bore 126 receives a locator pin (not shown) formed upon the coilbobbin to position the bobbin upon the coil spacer 82. As best seen inFIG. 11, in the preferred embodiment, three crush ribs 130 are formedupon the inner surface of the locator bore 126. The crush ribs 130cooperate with the bobbin locator pin to secure the bobbin upon the coilspacer 82. It will be appreciated, however, that the invention also canbe practiced with more or less crush ribs than are shown in FIG. 11. Aswill be explained below, the retention of the coil bobbins upon the coilspacer 82 enhances the electrical connection of the coil leads toelectrical traces deposited upon the PCB 84. In the preferredembodiment, the coil leads are wave soldered to the electrical traces;however, the invention can be practiced using any conventional processfor soldering, wielding or press fitting can be use for forming anelectrical connection, such as, for example, reflow soldering, laserwelding or a press fit connection.

As shown in FIG. 11, a first raised portion 120A and a second raisedportion 126A are formed upon the surface of the coil support ring 98.The first raised portion 120A extends around the kidney-shaped aperture120 while the second raised portions 126A extends around the locatorbore 126. The thickness of the raised portions 120A and 126A determinethe vertical displacement that occurs when the finger 112 is flexed;and, in turn, the force exerted by the tab 114 upon the flux casing andcoil.

As best seen in FIG. 8, a pair of coil spacer locator posts 132 (oneshown) extend in an upward direction from the upper surface of the coilspacer 82. A plurality of crush ribs 133 are formed on the base of eachof the locator posts 133. The coil spacer locator posts 132 and crushribs 133 cooperate with corresponding coil spacer locator apertures 134formed through the PCB 84 to locate and retain the coil spacer 82 uponthe PCB 84. As best seen in FIG. 12, one of the coil spacer locatorapertures 134 has a circular shape while the other has an oval shape. Itis contemplated each of the apertures 134 receives one of the spacerlocator posts 132. The oval shaped aperture allows the coil spacer 82 topivot about the locator post 132 that extends through the circular oneof the apertures 134. The resulting movement of the coil spacer 82relative to the PCB 84 provides compensation for manufacturingtolerances.

As shown in FIGS. 8 and 9 a pair of bosses 136 are formed in the coilspacer base and extend in an upward direction from the upper surface ofthe coil spacer 82. A stepped bore 137 having a wider diameter endportion extends through each of the bosses 136. The function of thestepped bore 137 will be explained below.

Returning to the plan view of the PCB 84 shown in FIG. 12, a pair ofhousing locator apertures 138 also are formed through the PCB 84. Itwill be appreciated that the drawing of the PCB 84 shown in FIG. 12 hasbeen simplified for clarity. Similar to the coil spacer locatorapertures 134, one of the housing locator apertures 138 has a circularshape while the other has an oval shape. The housing locator apertures138 function to position a coil spacer/PCB assembly within the housing92 by receiving a pair of housing locator posts 140 that extend in adownward direction from the inside of the housing 92, as shown in FIG.13. Thus, similar to the coil spacer locator posts 132, the oval housinglocator aperture allows the PCB 84 to pivot about about the housinglocator post 140 that extends through the circular one of the apertures138. The resulting relative movement between the PCB 84 and housing 92provides compensation for manufacturing tolerances.

Also shown in FIG. 13 are a plurality of pins 142 that extend from anECU electrical connector 144 formed upon the housing 92. In thepreferred embodiment, the housing 92 is injection molded from a plasticmaterial. Upon assembly of the ECU 80, the ends of the electricalconnector pins 142 are received by a plurality of connector apertures146 formed through the PCB 84. Similarly, clusters of coil apertures 148are formed through the PCB 148. In the preferred embodiment, eachcluster includes six coil apertures 148 with pairs of apertures 148 ineach cluster receiving the lead ends from three solenoid coils 88;however, the invention also can be practiced with the coil apertures 148arranged differently (not shown) upon the PCB 84. A pair of motorapertures 150 receive the ends of the motor spade connectors 106 whilefour pressure sensor apertures 152 receive the ends of the pressuresensor connector pins 109. The electrical connectors extend through theapertures formed through the PCB 84. Upon soldering, the connectors willbe electrical contact with electrical traces (not shown) formed upon thesurface and the inner layers of the PCB 84.

As best seen in FIG. 13, a continuous bead 154 of resilient materialextends about the perimeter of the lower edge of the housing 92. Uponassembly, the bead 154 forms a seal between the ECU 80 and the surfaceof the hydraulic valve body 95, as shown in FIG. 14. A plurality ofapertures 156 formed in the corners of the housing 92 receive thethreaded fasteners 94 that secure the ECU housing 92 to the hydraulicvalve body 95.

As best seen in FIG. 15, the housing locator posts 140 include slots 158formed in the ends thereof. Barbs 160 extend from the ends of each ofthe posts 140. Crush ribs 162 extend in a radial direction from the baseof each of the locator posts 140. Upon assembly of the ECU 80, thelocator posts 140 first pass through the housing locator apertures 138in the PCB 84. The post slots 148 are then compressed to allow the barbs160 to enter into the reduced diameter portion of the stepped bore 137formed in the coil spacer bosses 136. The resiliency of the locator postmaterial then urges the barbs 160 apart upon entry of the barbs 160 intothe wider diameter portion of the stepped bore 137. Additionally, asalso shown in FIG. 15, the crush ribs 162 press against the surface ofthe apertures 138 formed in the PCB 84. Thus, the barbs 160 and crushribs 162 cooperate with their respective apertures 137 and 138 formedthrough the coil spacer 82 and PCB 84 to retain the coil spacer 82 andthe PCB 84 upon the cover 92.

The invention also contemplates a coil bobbin structure that provides amechanical alignment of the solenoid coils 88 within their flux casings90, as illustrated in FIG. 16. A kidney-shaped coil lead support tower170 extends in an axial direction from one end of the solenoid coilbobbin (not shown). The kidney shape of the coil lead support tower 170corresponds to the shape of the kidney shaped openings 120 formedthrough each of the coil support rings 98 of the coil spacer 82. Twocoil leads 172 extend from the coil lead support tower 170. Ends 173 ofthe coil winding extend through axial slots (not shown) formed in thesurface of the support tower 170 and are wrapped around the bases of thecoil leads 172. The coil winding ends 173 are soldered to the coil leads172. Upon insertion of the solenoid coil 88 into the flux casing 90, thecoil lead support tower 170 extends through a similar kidney-shapedopening 174 formed through the closed end of the flux casing 90.Additionally, a coil locator post 176 formed upon the same end of thesolenoid bobbin (not shown) extends through a second opening 178 formedthrough the closed end of the flux casing 90. In the preferredembodiment, the coil lead support tower 170 and the coil locator post176 are integrally formed with the coil bobbin (not shown).

Upon assembly of the solenoid coil 88 and flux casing 90 upon the coilspacer 82, the coil leads 172 extend through the kidney-shaped opening120 formed through the coil support ring 98 with one of the coil leads172 passing on each side of the rectangular spacer 122. The coil leadsupport tower 170 is received within the kidney shaped opening 120 whilethe crush ribs 124 formed within the opening 120 co-operate with thesupport tower 170 to retain the solenoid coil 88 and flux casing 90 uponthe coil spacer 82. Additionally, the coil locator post 176 is receivedby the corresponding locator bore 126 formed in the coil support ring 98opposite from the kidney-shaped opening 120. The crush ribs 130 formedwithin the locator bore 126 co-operate with the coil locator post 176 toalso retain the solenoid coil 88 and flux casing 90 upon the coil spacer82.

The present invention also contemplates a method for assembling an ECU80 that is illustrated by the flow chart shown in FIG. 17. In functionalblock 180, each of the solenoid coils 88 is inserted into a flux casing90 with the lead support towers 170 and locator pins 176 extendingthrough the corresponding openings 174 and 178 in the closed end of theflux casings 90 to form coil assemblies 91. Each of the coil assemblies91 is mounted upon a coil spacer 82 in functional block 182 by insertingthe upper portions of the lead support towers 170 and locator pins 176into the corresponding openings 120 and 126 in a coil support ring 98.

In functional block 184, the coil spacer 82 is mounted upon a PCB 84with the coil spacer locator pins 132 extending through thecorresponding openings 134 in the PCB 84. Additionally, the coil leads172 extend through corresponding apertures 148 formed through the PCB84. Similarly, the ends of the motor and pressure sensor electricalconnectors 106 and 109 extend through corresponding apertures 150 and152 formed through the PCB 84. In functional block 186, the ends of thecoil leads 172 and the motor and pressure sensor electrical connectors106 and 109 are electrically connected to the PCB via and traces to forma PCB and coil spacer assembly. The coil leads 172 and connectors 106and 109 for the motor and pressure sensor contact electrical tracesdeposited upon the surface of and inner layers of the PCB 84. While wavesoldering is shown as the preferred embodiment, it will be appreciatedthat other conventional soldering techniques also may be utilized tomake the electrical connection.

The PCB and coil spacer assembly is inserted into a housing in 92functional block 188 with the housing locator pins 140 being received byand retained within the corresponding apertures 138 and 134 formedthrough the PCB 84 and coil spacer 82. At the same time, the ends of thehousing electrical connector pins 142 are received in correspondingapertures 146 that are formed through the PCB 84. Then, in functionalblock 190, the ends of the electrical connector pins 142 are soldered tothe corresponding apertures and electrical traces of the PCB 84 to forman ECU 80. In the preferred embodiment, the electrical connectors arewave soldered to the electrical traces; however, the invention can bepracticed using any conventional process for soldering, wielding orpress fitting can be use for forming an electrical connection, such as,for example, reflow soldering, laser welding or a press fit connection.The present invention contemplates that the size and shape of the coilspacer 82 allows access for soldering or welding of the electricalconnector pins 142. Alternately, the connector pins 142 can be press fitto the PCB 84. Finally, in functional block 192, the ECU 80 is mountedupon a hydraulic valve body 95 and secured thereto with a plurality offasteners 94.

As shown in FIG. 14, the coil assemblies 91 extend into a recess 200formed in the upper surface of the valve body 95. The bobbin included ineach of the coil assemblies 91 receives a solenoid valve sleeve 202 thatcontains an axially movable armature (not shown). Also, upon assembly ofthe ECU 80 upon a valve body 95, a pressure sensor mounted upon thevalve body 95 and its electrical connector is completely enclosed withinthe assembled unit. Similarly, the motor electrical connector iscompletely enclosed within the assembled unit.

As described above, upon assembly of the ECU 80 upon a hydraulic valvebody 95, the resilient members 112 urge the flux casing against thesolenoid valve sleeve 202, as illustrated in FIG. 14. The resultingcontact between the flux casing and valve body 95 enhances both the fluxpath for the magnetic field generated by each of the solenoid coils andthe transfer of heat from the coils to the valve body. Since the valvebody 95 is typically metal, it forms a heat sink for the solenoid coils88. As shown in FIG. 14, flux rings 204 are disposed between the lowerend of each of the coils 88 and the upper surface of the valve body 95.The flux rings 204 can be either included in the coil assemblies 91 orformed integrally upon the solenoid sleeves 202. In either case, theflux rings are formed from a ferro-magnetic material, such as, forexample, steel, and are conductive to both flux and heat. Alternately,the flux rings can be omitted (not shown) with the result that the lowerends of the bobbins directly contact the valve body surface.

It will be appreciated that the coil spacer 82 shown in the figures anddescribed above is exemplary and that the configuration of the coilspacer can be different from that which has been shown. For example,another coil spacer may receive more or less solenoid coils.Additionally, the invention also can be practiced with the pressuresensor connector and/or motor connector omitted and an overmoldedleadframe can be substituted for the PCB.

It will be noted that the invention compensates for manufacturingtolerances in both the vertical and horizontal directions for assemblyof ECU's upon hydraulic valve bodies.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

1. A control unit for a vehicle brake system, the control unitcomprising: a housing adapted to be mounted upon a hydraulic valve body;a circuit substrate mounted within said housing; a coil spacer mountedupon said substrate; said coil spacer including at least one coilsupport ring having a resilient member extending in a radial directionfrom the edge of said ring into the center of said ring; and a solenoidcoil and flux casing assembly mounted upon said coil spacer ring; saidsolenoid coil and flux casing assembly flexing said resilient membersuch that said resilient member urges said flux casing away from saidcoil spacer.
 2. A control unit according to claim 1 wherein said coilspacer also includes an electrical connector for at least one pressuresensor.
 3. A control unit according to claim 2 wherein said coil spacerfurther includes an electrical connector for a pump motor.
 4. A controlunit according to claim 3 wherein said coil spacer includes a pluralityof coil support rings and further wherein a plurality of solenoid coilsare mounted upon said coil spacer with each solenoid coil correspondingto one of said coil support rings.
 5. A control unit according to claim3 wherein said housing includes at least one locator post extending fromsaid housing and further wherein said circuit substrate and coil spacereach have at least one locator aperture formed therethrough, saidlocator apertures co-operating with said housing locator post toposition said circuit substrate and coil spacer within said housing. 6.A control unit according to claim 5 wherein said locator aperture is afirst aperture and circuit substrate and said coil spacer each include asecond locator aperture, said first aperture being circular and saidsecond aperture being non-circular and further wherein said housingincludes a second locator post with said first and second locator postsextending through said first and second apertures such that saidnon-circular aperture allows movement of said circuit substrate and saidcoil spacer relative to said housing.
 7. A control unit according toclaim 5 wherein said coil support rings are connected by webs thatextend in a radial direction between pairs of said coil support rings,said webs defining a lattice-like structure.
 8. A control unit accordingto claim 5 wherein said housing locator post has a slotted end with atleast one barb formed thereon and further wherein said coil spacerlocator aperture includes a stepped bore whereby said slot allows saidlocator post to pass through a smaller diameter portion of said steppedbore with said barb co-operating with a larger diameter portion of saidstepped bore to secure said coil spacer within said housing.
 9. Acontrol unit according to claim 5 wherein said coil spacer support ringhas an aperture formed therethrough, said aperture including at leastone crush rib extending therein and further wherein said solenoid coilhas a lead support post that extends through said support aperture, saidlead support post cooperating with said crush rib to retain said coilupon said coil spacer.
 10. A control unit according to claim 9 whereinsaid aperture in said coil spacer support ring is a first aperture andsaid coil spacer support ring has a second aperture formed therethroughand further wherein said solenoid coil also has a locator post formedthereon that extends through said second support ring aperture wherebysaid solenoid coil is positioned upon said coil spacer.
 11. A controlunit according to claim 10 wherein said second aperture has at least onecrush rib extending therein and further wherein said solenoid coillocator post cooperates with said crush rib to retain said coil uponsaid coil spacer.
 12. A control unit according to claim 5 wherein saidcircuit substrate is a printed circuit board, said printed circuit boardhaving a plurality of components mounted thereupon.
 13. The control unitaccording to claim 1 further including a hydraulic valve body adapted tobe connected to a vehicle hydraulic brake system, said hydraulic valvebody having at least one solenoid valve mounted thereon corresponding tosaid solenoid coil and flux casing assembly, said housing beingremovably attached to said hydraulic valve body and toward said valvebody.
 14. The control unit according to claim 13 wherein a pressuresensor is mounted upon said hydraulic valve body and further whereinsaid coil spacer also carries a pressure sensor electrical connector,said pressure sensor electrical connector being enclosed within thecontrol unit and electrically connecting said pressure sensor to saidcircuit substrate.
 15. A control unit according to claim 14 wherein saidcoil spacer also carries a motor electrical connector, said motorelectrical connector connecting a pump motor carried by said hydraulicvalve body to said circuit substrate and being enclosed within thecontrol unit.
 16. A method for assembling a control unit for a vehiclebrake system, the method comprising the steps of: (a) providing a coilspacer that includes a base having at least one coil support ring, thecoil support ring including resilient member extending in a radialdirection from the edge thereof and into the center of the support ring;(b) mounting at least one solenoid coil and flux casing assembly uponthe coil spacer ring with the coil and flux casing assembly flexing theresilient member such that the resilient member urges the flux casingaway from the coil spacer base; (c) mounting the coil spacer upon acircuit substrate to form an assembly; (d) inserting the circuitsubstrate and coil spacer assembly into a housing.
 17. A method forassembling a control unit according to claim 16 further including thestep of: (e) mounting the housing upon a hydraulic valve body.